This invention relates to an industrial robot control method. More particularly, the invention relates to an industrial robot control method for use in a system having a machine tool, a numerical control device for controlling the machine tool, an industrial robot and a robot control device for controlling the industrial robot. A plurality of NC programs are stored in the numerical control device, and an NC program selection signal is generated by the robot control device to cause the numerical control device to execute numerical control processing based on the NC program corresponding to the selection signal.
As shown in FIG. 1, a system having a machine tool for subjecting a workpiece to predetermined machining and an industrial robot for servicing the machine tool (e.g., loading and unloading workpieces, changing tools and cleaning machining scraps), is provided with a numerical control device NCU for controlling the machine tool MAC and with a separate robot control device RCU for controlling the industrial robot RBT. The numerical control device NCU and the robot control device RCU possess respective internal memories MMN, MMR. The memory MMN stores an NC program in accordance with which the machine tool subjects the workpiece to predetermined machining, while the memory MMR stores a robot program comprising a number of items of robot command data for prescribing robot motion. Processors PRN, PRR located within the respective numerical and robot control devices NCU, RCU read the machining data and robot command data out of the corresponding memories MMN, MMR in sequential fashion and control the machine tool MAC and the industrial robot RBT on the basis of the machining data and robot command data, so that machining and robot services may be executed as commanded. In FIG. 1, TP denotes a paper tape bearing a punched machining program read into the memory MMN by a tape reader (not shown). TB represents a teaching box, MX, MZ designate motors for driving the machine tool, and CPN, CPR denote ROMs (read-only memories) which store the respective control programs.
In a conventional system, the same machining operation is performed continuously a considerable number of times. With the method of the prior art, therefore, only a single NC program, selected depending upon the kind of machining to be performed on the workpiece, is stored beforehand in the memory MMN, and the robot control device is pre-taught only a single robot program, with the desired NC machining operation and robot services being carried out based on the NC program and robot program. Then, whenever the predetermined number of machining opeations ends and a different machining operation is to be performed, activities are halted temporarily to load a different NC program and teach a different robot program.
While the foregoing prior-art method is suitable for performing the same machining and the same robot services continuously for, say, a full day, it is unfit for instances where the machining operation and robot services are required to be changed one after another. In other words, according to the conventional method, the operator must intercede to perform the loading and teaching tasks whenever the machining operations and robot services change. This results in markedly diminished efficiency and makes it impossible for the method to be applied to unmanned plants or the like.